@boredboredboredboredbored I'll start by saying it is fantastic that your DD is doing so well in her English literature, I love it and did study it for degree back in the stone age.
Oxbridge is notoriously hard to get into, Oxford do look at GCSE grades, Cambridge lean toward year 12 progress. Ds is looking at Cambridge so the only information I have on Oxford is below.
We recently, before lockdown, attended an event put on by our son's sixth form college for "competitive entries" so medicine, dentistry, vetinary and anyone applying to Oxbridge as the UCAS date is October not January like every other university. Here are some facts and figures from that evening that were on a slide show.
In 2018 the number of applicants to Oxford was 21,515, they offered places to 3,840, number of students admitted was 3,309, so 15% of all applicants actually got in. I don't know how many places there are for each course. (I know for maths they usually make the admissions grades or exceed them but fall short on the maths test.)
Most Oxbridge applicants have at least 5 grade 7's and above for GCSE but the vast majority have a lot more higher grades. Grades 8 & 9 are considered the same for Oxford.
For Oxford specifically, A levels wise (according to UCAS collated data from 2017 and 2018 A level rounds) students achieved these grades
42.3% got A A A*
26.2% got A A A
19.4% got A* A A
6.5% got A A A
5.6% got "other"
Oxbridge is cut throat, but they have X number of places and X number of people are accepted there. So students do get in.
My advice would be for you and your DD to look at the Oxford website and look at what steps she needs to take, they are looking for what she is doing above and beyond her A levels. ie if she wanted to do teaching, has she volunteered in a primary school, run an after school club, been a mentor to other students in lower years etc etc? It is kind of all well and good to say you love something, but they want to see it.
There are summer schools in year 12, (Sutton Trust) so you need to look at that now, there are usually masterclasses too put on by colleges. Google will help with that.
I'll also put this here which is about contextual data, which is considered when a student applies to I believe any university. We come under a low POLAR postcode which works in Ds's favour. I know Cambridge is looking at first person in the family to go to uni applicants favourably too.
Oxford will no doubt have a YouTube channel and probably and English subject one, but here is a link for Eve Bennett who did get into Oxford to study English Literature. She is classed as a "StudyTuber" someone who promotes study along with Jack Edwards and UnJaded Jade. All 3 applied to Oxford.
I hope this helps. We found these things out in a rush at the start of year 12 after Ds1 was chosen for an outreach program by Cambridge uni. Before then he hadn't considered it because he didn't think he was good enough despite achieving incredible GCSEs.